Method of removing vesicant particles



Patented Feb. 6, 1%]51 METHOD OF REMOVING VESICANT PARTICLES Joseph S.Reichert, Metuchen, N. J ane] Ralph W. Peakes, Edgewood Arsenal, Md.,assignors to theUnited States of America as represented the Secretary ofWar No Drawing. Application June 1 9 31, Serial No. 542,686

Claims. (Cl. 8--128) (Granted under the act of March 3; 1883, as amendedApril 30, 1928; 370 0. G. .757)

This invention relates in general to protective clothing and moreparticularly has reference to a process of treating material forrendering it resistant to vesicant gases and vapors, and to the productresulting from the treatment. Previous to this time, it has beenattempted to fix chlorine on material for protecting against ,such gasesas mustard, but the impregnated cloth has increased in weight ,and hasbeen characterizedby stickiness. Also,the permeability of the ,same hasoften been lowered to such an extent as ,to make clothing made ofmaterial so treated, uncomfortable to the wearer.

A primary object of this invention is to provide material relativelyimpermeable tovesicant gases or vapors. r

, Another object of this invention is to provid materialhavingsemi-permeable properties, that 'is,', material which is permeable toair and inert gases, but impermeable to mustard gases and similarsubstances. 7

Another object of this invention is to devise a :process forproducingmaterial having properties renderingthe same impermeable to, mustardgases and substances having similar properties. Yet another object ofthis inventionis toprolvide a process for fixing chlorine on textilemate- -rial without appreciably affecting the desirable permeablecharacteristics thereof. a

' i A further object of this invention is to provide a process forchlorinating material to render the same impervious to mustard gas andsimilar substances withoutmaterially increasing the weight 'ofthe-material. i i

1 Stillanbther object of this invention is to devise a process oftreating clothing-to render the same impervious to vesicant and toxicgases or vapors, such as mustard "gas, 'lewisite and similar substances;A'still' furtherobject of this invention is" to devise a process forfixing chlorine 'in material to render the same" impervious to m i'stardgas and similar'substanc'es 'without;appreciap y changing "the dsiramphysical characteristics thereof With these and other objectsin view",them- I vention consists in the ingredients and'stepstolbe hereinafterset'forth'and caimd-withthe em rstanding thatQthe several necessarysubstanees and 'compgunds employed'incarrying out the pivention and thesteps involved the necessary V '2 procedure, may be widely variedwithout departing from the spirit of the invention or the scope of theappended claims.

The present invention consists briefly in directly fixing chlorine by achemical combination on material having the characteristics of wool, soas to render the same impervious to mustard gas and similar vesicant andtoxic gases. In preparing the material, wool or similar substances arechlorinated by subjecting them to treatment with hypochlorous acid,acidified hypochlorite salts or organic hypochlorites.

This invention is based on thefact-that active chlorine in the form offree chlorine, hypochlorite, chloramine, or chloramide will react withmustard gas, or lewisite. to form non-vesicant compounds, or compoundswhich are much less vesicant than mustard gas or lewisite. Wool isconsidered to be composed of a protein substance, known as keratin. Ithas been found that, when wool is subjected to the action of chlorine,some sort of a reaction takes place between the chlorine and the wool..It has been stated that the reaction between the chlorine and the woolproduces chloramines. However, it has been found that in some instancesno chloramines have been formed. Regardless of the theory of thereaction which takes placebetween the wool and the chlorinating agent,there is a change effected in the characteristic of the Wool which isdesirable for certain purposes, among which is that of rendering mustardgas and similar substances non-vesicant. V

We have found that, by chlorinating woolaccording to the various methodsherein set forth, a product is obtained which is impervious .to mustardgases and similar compounds employed -in-chemical warfare. In theprocesses as hereinafter set 'forth,-we have succeeded in directlyfixing active chlorine to wool by a chemical combination.

In developing the present invention, we discovered that active chlorinemay be directly fixed in wool to render the same impervious tomustardgases and'sin'iilar chemical compounds by three distinct types ofreagents; 1

These 'chlorinating reagents aref 1. Organic hypochlorites 2. Acidifiedhypochlorite salts 3. I-Iypochlorous acid *woo1and"simi1armaterial torender'the sen-1e material.

impervious to mustard gases and compounds having corresponding vesicantproperties. By subjecting the wool or other material to the action of anorganic hypochlorite, such as tertiary butyl hypochlorite under properconditions, a relatively large percentage of chlorine may beincorporated therein.

Chlorination of the wool may be effected by merely subjecting it to theaction of the tertiary alkyl hypochlorite for a definite period of time.It has been found, however, that the speed of the chlorinating actionmay be controlled 'by reg-ulating the moisture content of the wool orother material under treatment prior to the chlorinating reaction.

The moisture content may be regulated by allowing the moisture in thematerial to :come to equilibrium with an atmosphere having a controlledrelative humidity. This may be accomplished by suspending the materialin a cham-' bercontaining an atmosphere of a definite hu- Lmidity or bysubjecting the material to a moisture "saturated atmosphere for adefinite time.

Of course, any other method of regulating the moiscontent of the wool orother material undergoing treatment has on the speed and extent of achlorinating reaction.

Relative Active Chlorine Humidity Temperamle in the Wool Per cent HoursC. Per cent ,It will be seen from the foregoing tabulation that bycontrolling the moisture content of the wool or other material, as highas 5% of active chlorine may be introduced therein by subsequentlysubjecting it to a tertiary alkyl hypochlorite under the conditions setforth in the above tabulation. This may be accomplished without causingany appreciable damage to the The values given in the above tabulationwere obtained by treating woolen material with tertiary butylhypochlorite.

' fiIn one example upon which the above tabulation is based, themoisture in the woolen material was allowed to come to equilibrium withan 'atm'osphere of a controlled relative humidity of 8'l-%'=at-'25 C.-After this treatment, the material having a definite moisture contentwas immersed in a tertiary butyl hypochlorite main-* tained at atemperature of 40 C. The material was sub ected to the chlorinatingagent for about hours and subsequently to the chlorinating treatment waswashed with carbon tetrachloride. s ...In this instance, approximately5% of active nq-uately -forthis purpose, but .we wish it to be see n peY tin eth tesks eeeifl e ite- 4 be employed as found convenient. Thistreatment accelerates the subsequent chlorinating reaction and allows agreater amount ofchlorine to be introduced into the wool or similarmaterial without any damage thereto.

In carrying out the process involving the use of an acid inhibitingbuffer, the Wool or other material under treatment may be immersed in asolution of sodium acetate or other acid inhibiting buffer toincorporate the same in the material. We have found that by treating thematerial with a 1% solution of sodium acetate and incorporating thesolution therein to the extent of 1 times the weight of material givessatisfactory results. Any suitable methods for regulating the quantityof solution in the material may be employed. After subjecting thematerial to the solution of the acid inhibiting buffer, the material isdried, leaving a definite amount of the acid inhibiting buffer in thematerial, depending upon the concentration of the solution and thequantity of the solution taken up by the material.

Good results have been obtained by impregnating the material with about1 by Weightof acid inhibiting buffer. While specific quantities havebeen mentioned above, we wish it to be clearly understood that they aregiven merely by way of example, and that varied quantities of the acidbuffer may be employed.

After incorporating the buffer in the material to be treated, themoisture content of the dry impregnated Wool may then be regulated byallowing it to come to equilibrium with the moisture in an atmospherehaving a predetermined relative humidity. When a definite predeterminedmoisture content is established in the material, it may be immersed in asolution of tertiary butyl hypochlorite maintained at a temperatureeffective for chlorinating for a predetermined time. For instance, ithas been found that chlorination suitable for rendering the materialimpervious to mustard gas and similar vesicant compounds may be effectedby establishing .a moisture content in the material effected bysubjecting it to an atmosphere having a relative humidity ofapproximately 81% at 25 C., and immersing the conditioned material in asolution of tertiary butyl hypochlorite at a temperature approximating34 C., for a period of 4 hours.

After chlorination, the wool may be washed with carbon tetrachloride toremove the excess tertiary butyl hypochlorite. It has been found that.by treating wool or other materials as above set forth, as high as 8% ofactive chlorine (based on the weight of the wool) may be fixed in thematerial without damaging the same.

We wish it to be clearly understood that the conditions of chlorinationmay be varied over a relatively wide range. For instance, the reactionmay be controlled by fixing the moisture content of the material priorto treatment and the chlorinating reaction may be further controlled byvarying the time and/or temperature of the chlorinating treatment.Control of the chlorinating treatment may also be effected by dilutingthe tertiary alliyl hypochlorite with carbon tetrachloride or otherrelatively inert solvents. While in describing the process ofchlorinating wool andsimilar materials, specific mention has been madeof tertiary butyl hypochlorite, we wish it to be clearly understood thattertiary amyl hypochlorite may be just as fiflectively employed astertiary butyl hypochlo- Another method of chlorinating wool and similarsubstances to impart characteristics thereto desirable for protectingmaterials against mustard gas and similar substances, is to subject thematerial to an acidified sodium hypochlorite solution. For instance, asodium hypochlorite solution, acidified with glacial acetic acid may beemployed for fixing as high as 3% of active chlorine in the materialwithout dam aging the same.

Of course, acidified solutions of other hypochlorite salts may beemployed. For instance, other alkali metal salts of hypochlorous acidmay be employed.

The following specific example will serve as an illustration of theprocedure, but it is intended that the invention not be limited thereby,since results can be obtained by widely varying the specific compoundsemployed and the quantities used in carrying out the followingprocedure. Twelve grams of the cloth to be treated may be immersed in1457 cc. of water, to which 240 cc. of sodium hypochlorite solution(containing 11.7% of active chlorine and 3.5% of free sodium hydroxide)is added. To this solution, 63 cc. of glacial acetic acid is immediatelyadded while the solution is agitated. Agitation is maintained and thetemperature of the solution is held substantially constant atapproximately 23 C. The cloth may be allowed to remain in the solutionunder the above conditions for about 1 minutes. After subjecting thematerial to this treatment, it is then thoroughly washed with water. Ithas been found that about 3% of active chlorine may be fixed in the woolby the above procedure.

It has also been found that wool and similar materials may bechlorinated to render them substantially impervious to mustard gas andcorresponding substances by subjecting the material to a purehypochlorous acid solution. The solution employed may be either purehypochlorous acid or hypochlorous acid prepared by the action ofchlorine on water in the presence of calcium carbonate. By subjectingthe wool or other material to treatment with hypochlorous acid as setforth above, we have succeeded in fixing about 3% of active chlorine inthe material without appreciable damage.

It is also possible to fix active chlorine in wool and similarsubstances by means of free chlorine without material damage to thesubstance. In this instance, however, only relatively small amounts ofchlorine may be fixed to the material without damaging the same. We havesucceeded in fixing approximately .5% of chlorine in the material by thepreceding method.

In the foregoing description, we have illustrated the inventionwith'reference to treatment of the wool or similar material bysubjecting it to the action of particular compounds and conditions. Itshould be clearly understood, however, that desirable and effectiveresults may be obtained by employing equivalent compounds and by varyingthe condition of the material undergoing treatment, and the treatingconditions over relatively wide ranges.

Material such as wool, when treated according to the methods herein setforth, serves very efficiently for protecting against mustard gases andcorresponding vesicant gases. While the treated material having chlorinefixed therein is relatively impermeable or impervious to mustard gas,lewisite and similar substances, its permeability to air and gasesunaffected by the chlorine content of the cloth is practicallyunaffected. The material acts in the nature of a semi-permeablemembrane.

Desirability of this feature is obvious in that clothing made of thetreated material may be worn with considerable more comfort thanclothing which is impervious to all gases.

Vapors of mustard gas or corresponding vesicant compounds, uponcontacting with the treated material, react with the chlorine fixed inthe material to produce non-vesicant reaction products. It is believedthat the reaction takes place according to the ratio of one molecule ofchlorine to one molecule of mustard gas.

In the foregoing description, the processes and product have beenmentioned in connection with wool and similar materials. The process is,of course, applicable to other fibres of animal and other origins.

While we have described the preferred embodiments of our invention, wewish it to be understood that we do not confine ours-elves to theprecise steps or ingredients set forth herein by way of illustration, asit is apparent that many changes and variations may be made therein bythose skilled in the art, without departing from the spirit of theinvention or exceeding the scope of the appended claims.

We claim:

1. A method of removing vesicant particles from vesicant contaminatedair which comprises passing the air through woolen material havingactive chlorine fixed thereon by chemical combination.

2. A method of removing vesicant particles from vesicant contaminatedair which comprises passing the air through woolen material which hasbeen treated with a compound from the group consisting of organichypochlorite, hypochlorite salts and hypochlorous acid.

3. A method, according to claim 2, in which the material has beentreated with an organic hypochlorite from the group consisting oftertiary butyl hypochlorite and tertiary amyl hypochlorite.

4. A method according to claim 2, in which the material has been treatedwith tertiary butyl hypochlorite.

5. A method according to claim 2, in which the material has been treatedwith tertiary amyl hypochlorite.

JOSEPH S. REICHERT. RALPH W. PEAKES.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,522,555 Trotman Jan. 15, 19251,781,415 Smith Nov. 11, 1930 2,132,345 Reichert et a1. 7 Oct. 4, 1938FOREIGN PATENTS Number Country Date 13,088 Great Britain 1911

1. A METHOD OF REMOVING VESICANT PARTICLES FROM VESICANT CONTAMINATEDAIR WHICH COMPRISES PASSING THE AIR THROUGH WOOLEN MATERIAL HAVINGACTIVE CHLORINE FIXED THEREON BY CHEMICAL COMBINATION.